Brønsted-Acid-Promoted Diaza-Nazarov Cyclization to Access Tetrasubstituted Pyrazoles
ORGANIC LETTERS, cilt.27, sa.39, ss.11094-11099, 2025 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 27 Sayı: 39
- Basım Tarihi: 2025
- Doi Numarası: 10.1021/acs.orglett.5c03531
- Dergi Adı: ORGANIC LETTERS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, Chimica, MEDLINE, Nature Index
- Sayfa Sayıları: ss.11094-11099
- Orta Doğu Teknik Üniversitesi Adresli: Hayır
Özet
We have developed a new diaza-Nazarov cyclization for the synthesis of densely substituted pyrazoles. Treatment of N-acylazo substrates with 1-1.5 equiv of trifluoroacetic acid (TFA) as a Br & oslash;nsted acid promoter at 23 degrees C afforded hydroxypyrazole products in good to excellent yields (up to 99%). Reactions of substrates with secondary alkyl groups at the beta position of the alpha,beta-unsaturated carbonyl moiety gave minor amounts of dihydropyridazinone compounds as side products, proposed to form via an intriguing 6 pi electrocyclization.